Path-dependent effects of ultrasonic and annealing treatments on the multiscale structure and functionality of rice flour for savory rice pudding (wa gui) applications

Physical modification provides a sustainable strategy for tailoring rice flour functionality; however, the role of treatment sequence in dual physical modification remains insufficiently understood. This study investigated the sequence-dependent effects of ultrasonic treatment (UT) and annealing (ANN) on the multiscale structure, hydration behavior, pasting properties, water dynamics, rheological performance, and gel-forming ability of indica rice flour from Taichung Sen 17. Savory rice pudding ( wa gui ) was further used as a proof-of-concept application model. The ANN–UT sequence caused the greatest structural disruption, as indicated by the lowest median particle size (D 50 = 8.83 μm), relative crystallinity (15.23%), gelatinization enthalpy (0.25 J/g), peak viscosity (2068.66 cP), and final viscosity (3392.33 cP). These changes were accompanied by restricted swelling, higher water mobility, and weaker gel formation. On the contrary, the UT–ANN sequence retained greater structural continuity and reassociation capacity, as reflected by higher D 50 (10.43 μm), relative crystallinity (16.15%), gelatinization enthalpy (0.65 J/g), peak viscosity (4273.66 cP), and final viscosity (6913 cP). UT–ANN also promoted stronger water confinement and firmer wa gui gel formation. These findings indicate that UT–ANN and ANN–UT represent distinct path-dependent routes of modification rather than interchangeable dual treatments. Sequence control may therefore provide a non-chemical strategy for designing rice-based ingredients with tunable hydration, pasting, and gel-forming properties. Further molecular-level characterization and validation of applications are required to confirm the structural basis and practical feasibility of this approach.